As early as 1914 inventors were devising ways for the operator of a motor vehicle to observe the inflation pressure of tires as exemplified in U.S. Pat. No. 1,089,326 to Chilson. More recent examples of pressure indicators are found in U.S. patents to Bordwick, U.S. Pat. No. 3,357,240 (1967), and Yabor, U.S. Pat. No. 3,789,867 (1974). In earlier years, when tires and tubes were formed of natural rubber, they required much more attention relative to inflation since the material was porous and the tires tended to deflate by leakage through the walls. With the more recent use of synthetic rubber and tubeless tires, the tires retain the initial inflated condition for a relatively long time. Under these conditions a vehicle operator tends to become careless about checking his tires.
It is an object of the present invention to provide an inflation indicator which will register "under inflation" at a glance with no need to bend down and read any calibrated scale. A color signal will warn the observer if there is a deflation condition which requires attention.
It is a further object to provide a tire pressure indicator which can be readily mounted on a valve stem in a manner to depress the basic springbiased valve and substitute a secondary seal.
It is a further object to provide an indicator which can be readily removed so that the air supply nozzle to permit inflation can be applied to the standard valve stem.
Additional objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with details to enable persons skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the invention.